Friday, February 7, 2014

Describe and compare IPv4 and IPv6 addressing schemes.

IPv4
IPv4 stands for Internet Protocol version 4. It is the underlying technology
that makes it possible for us to connect our devices to the web. Whenever a
device access the Internet (whether it's a PC, Mac, smartphone or other
device), it is assigned a unique, numerical IP address such as 99.48.227.227.
To send data from one computer to another through the web, a data packet must
be transferred across the network containing the IP addresses of both devices.

IPv4 uses 32-bit addresses for Ethernet
communication in five classes, named A, B, C, D and E. Classes A, B and C have
a different bit length for addressing the network host. Class D addresses are
reserved for multicasting, while class E addresses are reserved for future use.

Class A has subnet mask 255.0.0.0 or /8, B
has subnet mask 255.255.0.0 or /16 and class C has subnet mask 255.255.255.0 or
/24. For example, with a /16 subnet mask, the network 192.168.0.0 may use the
address range of 192.168.0.0 to 192.168.255.255. Network hosts can take any
address from this range; however, address 192.168.255.255 is reserved for
broadcast within the network.

IPv6IPv6is the next generation protocol for
Internet networking. IPv6 expands on the current Internet Protocol standard
known as IPv4. Compared to IPv4, IPv6 offers better addressing, security and
other features to support large worldwide networks.In IPv6, IP addresses change from the current
32-bit standard and dotted decimal notation to a new 128-bit address system.
IPv6 addresses remain backward compatible with IPv4 addresses. For example, the
IPv4 address "192.168.100.32" may appear in IPv6 notation as
"0000:0000:0000:0000:0000:0000:C0A8:6420" or "::C0A8:6420".

Main reasons for
running out of IPv4.
The IPv4 protocol was created in 1981 like a technology supposed to last for a
very long time, with an addressing space of 4000 million of addresses, but the
enormous growth of the internet and the way the addresses were assigned
(classes A, B and C), resulted in a serious lack of addresses. There are
several methods that avoid the total run out of addresses: PPP/DHCP (address
sharing), CIDR (classless inter-domain routing) and NAT (network address
translation), but do not seem to be enough in a few years, specially having
into account the growing number of devices that need a permanent allocation of
an IP address (UMTS, DSL, etc), and the applications that are end-to-end, and
are not compatible with NAT (IPsec, VoIP, etc.).

Another problem is that, because of being designed many years
ago, the functionalities involved with security, mobility and quality are
handled by additional protocols, because they are not integrated in the
protocol itself.

So, these 2 problems, plus the fact of the great growth of
the number of elements in the routing tables motivated the necessity of a new
version of the protocol became very important, so a new working group of the
Internet Engineering Task Force (IETF) was created with the name: “IP next
generation” (IPng). And some time later, the name was changed to IPv6. The main
characteristics of this protocol had to be the following: